Wetting and detergent composition



Aug., 5, 1941. R, Q sWAlN 2,251,768

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Aug@ 5, 1941.

R. c. swAlN WETTING AND DETERGENT COMPOSITION Filed Sept. 29, 1938 2Sheets-Sheet 2 ONT.

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ATTORNEY.

Patented Au'g. 5, `1941 l UNITED STATES ,PATENT yfori-fici;

y 2,251,768 wE'rrINc. AND DETERGENT COMPOSITION Robert C. Swain, OldGreenwich,V Conn., assignor to American Cyanamid Company, New York,

N. Y., a corporation of Maine lApplication September 29, 1938, SerialNo. 232,375

Claims.

agents. Although vall the esters described in thatl patent have wet/tingand emulsifying properties, it has been found that those of the highestWetting and emulsifying power are the esters of sulfodicarboxylic acidswith aliphatic alcohols of 5-10 carbon atoms in the chain'.Unfortunately, however, the water solubility of these esters decreaseswith increase in the molecular weight of the esterifying alcohol used,so that these wetting agents cannot be marketed in the form of veryconcentrated solutions. Of course it is possible to sell the esters insolid form, which is a great advantage insofar as shipping and storageare` concerned, but some customers object to the product in this formbecause they experience difficulty in getting it into solution. On. theother hand, when a relativelyl dilute solution is marketed, such as aaqueous solutionfthe customer must pay shipping and storage rates onconsiderable amounts of water in order to obtain a product that isdirectly usable.

known concentrations. On this basis the'dioctyl ester of sulfosuccinicacid constitutes the cheapest and best wetting agenton the market at thepresent time, but it is easily possible that uctuations in the price ofother alcohols of 5-10 carbon atoms may change the commercial pictureand make the sulfosuccinic acid ester of some other alcohol a bettervalue. The present inven- I have now discovered that the esters ofsulfo- A.

f dicarboxylic acids with aliphatic alcohols of 5-10 carbon atoms, whichare the esters causing the 'greatest difficulties as regards lack ofwater solubility, can be solubilized by the addition of urea or itsderivatives. -The amount of urea to be used will depend, of course, onthe conentration in which the wetting agent solution is to be marketedand on the temperature, but I have found in general that about 1 to 3times as much urea asv ester should be used at the higher concentra-'tions' When the sulfodicarboxylie acid ester is to be marketed in lowerconcentrations, such as 10-20% solutions, this ratio can be loweredsomewhat. v

At the present time, wetting agents are evaluatedon a money basis asdetermined by the vDraves test, which is basedon the sinking time of acotton skein in wetting agent solutions of tion will be illustrated interms of dioctyl sulfosuccinate because of its present greatercommercial value, but it should be understood that this specicillustration is merely representative of the action of urea on anydialkyl sulfosuccinate in which the alkyl group contains from 5-'10carbon atoms, and that the invention in its broader aspects is notlimited tothe speciiic examples given.

On the attached drawings, Fig. 1 is a graph showing the solubility ofsodium dioctyl sulfosuccinate in urea solutions, illustrating theincrease in solubility at varying temperatures with increased ureaconcentrations, and

Fig. 2 is a triple point diagram showing the composition of a saturatedsolution containing urea and sodium dioctyl sulfosuccinate at vanyspecified temperature in terms of percent by weight of urea and percentby weight of the dialkyl sulfosuccinate, based on the weight of thefinal solutions.

Referring to Fig. 1, it will be seen that at 60 C. the dioctylsulfosuccinate isy soluble in lwater in amounts of less than 5%. In a20%` urea solution its solubility is doubled, and in a.40% so: lutionits solubility is more than quadrupled. The data. upon which the curvesof Fig. 1 are based was obtained by the synthetic method for thedetermination of solubility; a known weight of the wetting agent wasdissolved by warming with a given volume of urea solution of knownconcentration and the temperature was recorded at which, the mixturebecame cloudy on cooling.

By successively adding urea in known quantities yand recording theclouding points sets of solubility curves similar to those in Fig. 1have been obtained for the other members of the series. All these curvesare similar in shape, but differ among themselves with variations in theoriginal water solubility of the particular ester. For example, sodiumdiamyl sulfosuccinate and sodium dihexyl sulfosuccinate are about35'times as soluble in water as sodium dioctyl sulfosuccinate and muchless urea is required to form solutions of ordinary commercial strength.At room temperature 40 grams of these esters will dissolve in a liter ofless soluble than sodium dioctyl sulfosuccinate and more urea must beadded to obtain solutions of similar strength. For example, only gramsof sodium dinonyl sulfosuccinate 'can be dissolved in a liter of waterat 70 C. as compared with 60 grams of the dioctyl ester, and the didecylcompound is even less soluble. It is necessary to use 20% and 30% ureasolutions, respectively, to 0btain 10% solutions of these two wettingagents which are clear at room temperatures.

The triple point diagram shown on Fig. 2 was obtained by choosingrepresentative temperatures of C., 30 C., 50 C. and 75 C. andcalculating the coordinates from the data shown on Fig. 1. From Fig. 2values can readily be obtained which give the amount of urea required tosolubilize any given amount of sodium -dioctyl sulfosuccinate at anydesired temperature. For example, the amounts required to solubilize 5%and 10% solutions are illustrated in the following table A. 5% sodium B10% sodium dioctyl sulfosucdioctyl sulfosuccinate cinate Urea by Urea byweight Temp weight Temp Percent C'. Percent C.

The above iigures show the marked improvements in the limits ofsolubility of the sulfodicarboxylic acid esters included in the presentinvention which can be obtained by the addition of urea thereto. Anotherimportant characteristie of such mixtures is the corresponding increasein their rate of solution in water; while the esters themselves areronly slowly dissolved or dispersed even at elevated temperatures, theirmixtures with urea disperse rapidly. This characteristic overcomes theinherent objection to the marketing ofthese wetting agents in dry form,for dried mixtures of sulfodicarboxylic acid esters of aliphaticalcohols of 5-10 carbon atoms with l-6 times their weight of urea can bereadily dissolved in warm water or even in cold water by the customer toany desired strength of solution within the limits out-lined above.

Although simple physical mixtures of the wetting agent with urea arereadily soluble I have found, as another feature of the invention, thatvery intimate mixtures obtained by drying aqueous solutions containingthe wetting agent and urea are even more satisfactory. Such mlntions arepreferably spray-dried or drum-dried;

, that is to say, the solutions are spread overthe surface of aninternally heated rotating drum or are sprayed through the nozzle of acom-i mercial spray-drying machine and the product is collected as agranular spray-dried mixture'. For example, a mixture of 6 parts of ureawith 1 part of sodium dioctyl sulfosuccinate was dissolved in warm waterand sprayed through a revolving nozzle into a rising stream of hot airin an ordinary commercial spray-drying apparatus. In this case the airinlet temperature was 307 F. and the outlet temperature was 2'30F., andthe spray-dried product was recovered as a light, fluffy powder whichdissolved instantly 'when poured into water. Obviously, any ratio ofurea to wetting agent may be used in preparing such -spray-dried ordrum-dried compositions, depending upon the rate and strength ofsolution desired by the customer.

From the foregoing description, it will be seen that wetting anddetergent compositions of improved water solubility can be obtained fromany dlalkyl ester of a sulfodicarboxylic acid in which the alkyl groupscontain from 5 to 10 car bon atoms, simply by the -addition of urea.-The action of urea as a solubilizing agent is perfectly general asregards the wetting agents of this class, and by employing the methods.outlined above the solubility characteristics of any given wetting agentcan readily be determined. Accordingly, it is evident that the presentinvention provides an improved class of wetting and detergentcompositions which may be used to advantage in any of the fields wheresuch compositions have previously been employed and which can be morereadily applied by reason of their improved water solubility.

What I claim is:

1. A wetting and detergent composition comprising one part by weight ofan ester of sulfosuccinic acid with an aliphatic alcohol of 5 to 10carbon atoms, together with from 1 to 3 parts by weight of urea as asolubilizing agent therefor.

2. A wetting and detergent compositioncomprising a 10% aqueous solutionof an ester of sulfosuccinic acid with an aliphatic alcohol of 5-10carbon atoms together with urea in amounts of 1 to 3 times the weight ofsaid ester as a solubilizing agent therefor.

3. A wetting and detergent composition comprising a 10% aqueous solutionof sodium4 dioctyl sulfosuccinate together with from l to 3 times itsweight of urea as a solubilizing agent therefor.

4. A wetting and detergent composition comprising a granular spray-driedmixture of one part by weight of an ester of sulfosuccinic acid with analiphatic alcohol of 5 to 10 carbon atoms, together with from 1 to 3vparts by weight of urea as a solubilizing agent therefor.

5. A wetting and detergent composition comprising sodium ddioctylsulfosuccinate together with from 1 to 3 times its weight of urea as asolubilizing agent therefor.

ROBERT C. SWAIN.

